除其他事项外，我试图了解 OUTPUT_ARCH（arm）和 OUTPUT_ARCH（armv4）之间的区别。
假设我们有下一个文件（我使用here中的链接描述文件作为基础）：
main.c:
int main(void)
{
test_1();
test_2();
return 0;
}
main.lds:
OUTPUT_ARCH(arm)
SECTIONS
{
. = 0x10000;
.text : { *(.text) }
. = 0x8000000;
.data : { *(.data) }
.bss : { *(.bss) }
}
test_1.c:
void test_1(void)
{
return;
}
test_2.c:
void test_2(void)
{
return;
}
如果我们编译它并转储它的内容我们接下来：
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe test_1.c -c
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe test_2.c -c
c:\SysGCC\arm-elf\bin>arm-elf-objdump.exe -x test_1.o
test_1.o: file format elf32-littlearm
test_1.o
architecture: arm, flags 0x00000010:
HAS_SYMS
start address 0x00000000
private flags = 200: [APCS-32] [FPA float format] [software FP]
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000014 00000000 00000000 00000034 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000000 00000000 00000000 00000048 2**0
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000048 2**0
ALLOC
3 .comment 00000012 00000000 00000000 00000048 2**0
CONTENTS, READONLY
4 .ARM.attributes 00000010 00000000 00000000 0000005a 2**0
CONTENTS, READONLY
SYMBOL TABLE:
00000000 l df *ABS* 00000000 test_1.c
00000000 l d .text 00000000 .text
00000000 l d .data 00000000 .data
00000000 l d .bss 00000000 .bss
00000000 l d .comment 00000000 .comment
00000000 l d .ARM.attributes 00000000 .ARM.attributes
00000000 g F .text 00000014 test_1
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe -static -nostartfiles -T main.lds -o main.elf test_1.o test_2.o
c:\SysGCC\arm-elf\bin>arm-elf-objdump.exe -x main.elf
main.elf: file format elf32-littlearm
main.elf
architecture: arm, flags 0x00000112:
EXEC_P, HAS_SYMS, D_PAGED
start address 0x00010000
Program Header:
LOAD off 0x00008000 vaddr 0x00010000 paddr 0x00010000 align 2**15
filesz 0x00000028 memsz 0x00000028 flags r-x
private flags = 200: [APCS-32] [FPA float format] [software FP]
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000028 00010000 00010000 00008000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .comment 00000011 00000000 00000000 00008028 2**0
CONTENTS, READONLY
2 .ARM.attributes 00000010 00000000 00000000 00008039 2**0
CONTENTS, READONLY
SYMBOL TABLE:
00010000 l d .text 00000000 .text
00000000 l d .comment 00000000 .comment
00000000 l d .ARM.attributes 00000000 .ARM.attributes
00000000 l df *ABS* 00000000 test_1.c
00000000 l df *ABS* 00000000 test_2.c
00010014 g F .text 00000014 test_2
00010000 g F .text 00000014 test_1
但如果我将 OUTPUT_ARCH（arm）更改为 OUTPUT_ARCH（armv4），我会从链接器收到错误：
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe -static -nostartfiles -T main.lds -o main.elf test_1.o test_2.o
c:/sysgcc/arm-elf/bin/../lib/gcc/arm-elf/4.6.3/../../../../arm-elf/bin/ld.exe: error: test_1.o uses software FP, whereas main.elf uses hardware FP
c:/sysgcc/arm-elf/bin/../lib/gcc/arm-elf/4.6.3/../../../../arm-elf/bin/ld.exe: failed to merge target specific data of file test_1.o
c:/sysgcc/arm-elf/bin/../lib/gcc/arm-elf/4.6.3/../../../../arm-elf/bin/ld.exe: error: test_2.o uses software FP, whereas main.elf uses hardware FP
c:/sysgcc/arm-elf/bin/../lib/gcc/arm-elf/4.6.3/../../../../arm-elf/bin/ld.exe: failed to merge target specific data of file test_2.o
collect2: ld returned 1 exit status
可以通过指定 -mfloat-abi = hard 选项来修复它。在这种情况下，与以前的输出相比，私有标志存在差异：
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe -mfloat-abi=hard test_1.c -c
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe -mfloat-abi=hard test_2.c -c
c:\SysGCC\arm-elf\bin>arm-elf-objdump.exe -x test_1.o
test_1.o: file format elf32-littlearm
test_1.o
architecture: arm, flags 0x00000010:
HAS_SYMS
start address 0x00000000
private flags = 0: [APCS-32] [FPA float format]
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000014 00000000 00000000 00000034 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .data 00000000 00000000 00000000 00000048 2**0
CONTENTS, ALLOC, LOAD, DATA
2 .bss 00000000 00000000 00000000 00000048 2**0
ALLOC
3 .comment 00000012 00000000 00000000 00000048 2**0
CONTENTS, READONLY
4 .ARM.attributes 00000010 00000000 00000000 0000005a 2**0
CONTENTS, READONLY
SYMBOL TABLE:
00000000 l df *ABS* 00000000 test_1.c
00000000 l d .text 00000000 .text
00000000 l d .data 00000000 .data
00000000 l d .bss 00000000 .bss
00000000 l d .comment 00000000 .comment
00000000 l d .ARM.attributes 00000000 .ARM.attributes
00000000 g F .text 00000014 test_1
c:\SysGCC\arm-elf\bin>arm-elf-gcc.exe -static -nostartfiles -T main.lds -o main.elf test_1.o test_2.o
c:\SysGCC\arm-elf\bin>arm-elf-objdump.exe -x main.elf
main.elf: file format elf32-littlearm
main.elf
architecture: arm, flags 0x00000112:
EXEC_P, HAS_SYMS, D_PAGED
start address 0x00010000
Program Header:
LOAD off 0x00008000 vaddr 0x00010000 paddr 0x00010000 align 2**15
filesz 0x00000028 memsz 0x00000028 flags r-x
private flags = 0: [APCS-32] [FPA float format]
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000028 00010000 00010000 00008000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .comment 00000011 00000000 00000000 00008028 2**0
CONTENTS, READONLY
2 .ARM.attributes 00000010 00000000 00000000 00008039 2**0
CONTENTS, READONLY
SYMBOL TABLE:
00010000 l d .text 00000000 .text
00000000 l d .comment 00000000 .comment
00000000 l d .ARM.attributes 00000000 .ARM.attributes
00000000 l df *ABS* 00000000 test_1.c
00000000 l df *ABS* 00000000 test_2.c
00010014 g F .text 00000014 test_2
00010000 g F .text 00000014 test_1
这是否意味着 OUTPUT_ARCH（armv4）导致链接器仅为硬浮点生成输出？
一般来说， OUTPUT_ARCH（arm）和 OUTPUT_ARCH（armv4）之间有什么区别？
根据ld manual OUTPUT_ARCH（）指定特定的输出机器架构。
参数是BFD库使用的名称之一。
但除了一般信息之外，我没有找到关于BFD库的明确信息。
我使用来自here的arm-elf工具链（Binutils 2.22，GCC 4.6.3，Newlib 1.2.0，GDB 7.4）。
提前感谢您的帮助。
更新1：
此更新是对以下评论的回复。
我们现在使用的旧工具链的编译器-v输出：
Using built-in specs.
Target: arm-elf
Configured with: ../gcc-4.4.1/configure --target=arm-elf --host=i686-pc-mingw32 --with-cpu=xscale --without-stabs -nfp --prefix=/c/cross-gcc/4.4.1 --disable-nls --disable-shared --disable-__cxa_atexit
--enable-threads --with-gnu-gcc --with-gnu-ld --with-gnu-as --with-dwarf2 --enable-languages=c,c++ --enable-interwork --disable-multilib --with-gmp=/c/cross-gcc/4.4.1 --with-mpfr=/c/cross-gcc/4.4.1 -
-with-newlib --with-headers=../../newlib-1.17.0/newlib-1.17.0/newlib/libc/include --disable-libssp --disable-libstdcxx-pch --disable-libmudflap --disable-libgomp -v
Thread model: single
gcc version 4.4.1 (GCC)
我在示例中使用的较新工具链的编译器-v输出（SysGCC arm-elf）：
Using built-in specs.
COLLECT_GCC=arm-elf-gcc.exe
COLLECT_LTO_WRAPPER=c:/sysgcc/arm-elf/bin/../libexec/gcc/arm-elf/4.6.3/lto-wrapper.exe
Target: arm-elf
Configured with: ../gcc-4.6.3/configure --target arm-elf --enable-win32-registry=SysGCC-arm-elf-4.6.3 --prefix /c/gnu/auto/bu-2.22+gcc-4.6.3+gmp-4.2.4+mpfr-2.4.1+mpc-0.8+newlib-1.20.0-arm-elf/ --enabl
e-languages=c,c++ --disable-nls --with-newlib --with-headers=../newlib-1.20.0/newlib/libc/include --enable-interwork --enable-multilib --with-float=soft
Thread model: single
gcc version 4.6.3 (GCC)
旧编译器的 OUTPUT_ARCH（arm）和 OUTPUT_ARCH（armv4）的链接器输出没有区别。我想我应该先检查一下。 似乎这是对这个问题的回答。
我的目标是使用组合-mfpu=vfpv3 -mfloat-abi=hard，但根据Debian documentation和GCC 4.4.7 manual，GCC 4.4不支持此组合。
实际上，如果我尝试使用旧编译器使用-mfpu=vfpv3 -mfloat-abi=hard进行编译，则会返回错误：
sorry, unimplemented: -mfloat-abi=hard and VFP
仍然可以将-mfpu=vfpv3 -mfloat-abi=softfp与旧编译器一起使用，但根据this comparison，它为小例程提供了很大的开销。